Nuclear magnetic resonance spectroscopy of partially saturated diene polymers. II. 13C-NMR spectra of partially hydrogenated natural rubber, gutta percha, and cis-1,4-polybutadiene

1979 ◽  
Vol 17 (3) ◽  
pp. 919-921 ◽  
Author(s):  
Y. A. Shahab ◽  
R. A. Basheer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Natural Rubber ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Resonance Spectroscopy ◽  
13C Nmr Spectra ◽  
Partially Saturated ◽  
Gutta Percha

scholarly journals Study of the biologically active acyclic ureas by nuclear magnetic resonance

2020 ◽  
Vol 100 (4) ◽  
pp. 60-74
Author(s):  
А.А. Bakibaev ◽  
◽  
М.Zh. Sadvakassova ◽  
V.S. Malkov ◽  
R.Sh. Еrkasov ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Functional Groups ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Biologically Active ◽  
Resonance Spectroscopy ◽  
13C Nmr Spectra ◽  
Nuclear Magnetic

A wide variety of acyclic ureas comprising alkyl, arylalkyl, acyl, and aryl functional groups are investigated by nuclear magnetic resonance spectroscopy. In general, spectral characteristics of more than 130 substances based on acyclic ureas dissolved in deuterated dimethyl sulfoxide at room temperature are studied. The re-sults obtained based on the studies of 1H and 13C NMR spectra of urea and its N-alkyl-, N-arylalkyl-, N-aryl- and 1,3-diaryl derivatives are presented, and the effect of these functional groups on the chemical shifts in carbonyl and amide moieties in acyclic urea derivatives is discussed. An introduction of any type of substitu-ent (electron-withdrawing or electron-donating) into urea molecule is stated to result in a strong upfield shift in 13C NMR spectra relatively to unsubstituted urea. A strong sensitivity of NH protons to the presence of acyl and aryl groups in nuclear magnetic resonance spectra is pointed out. In some cases, qualitative depend-encies between the chemical shifts in the NMR spectra and the structure of the studied acyclic ureas are re-vealed. A summary of the results on chemical shifts in the NMR spectra of the investigated substances allows determining the ranges of chemical shift variations of the key protons and carbon atoms in acyclic ureas. The literature describing the synthesis procedures are provided. The results obtained significantly expand the methods of reliable identification of biologically active acyclic ureas and their metabolites that makes it promising to use NMR spectroscopy both in biochemistry and in clinical practice.

scholarly journals Qualitative and Quantitative Analysis of Heavy Crude Oil Samples and Their SARA Fractions with 13C Nuclear Magnetic Resonance

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 995
Author(s):  
Ilfat Rakhmatullin ◽  
Sergey Efimov ◽  
Vladimir Tyurin ◽  
Marat Gafurov ◽  
Ameen Al-Muntaser ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Crude Oil ◽  
Functional Groups ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectra ◽  
Sara Fractions ◽  
Nuclear Magnetic

Nuclear magnetic resonance (NMR) approaches have unique advantages in the analysis of crude oil because they are non-destructive and provide information on chemical functional groups. Nevertheless, the correctness and effectiveness of NMR techniques for determining saturates, aromatics, resins, and asphaltenes (SARA analysis) without oil fractioning are still not clear. In this work we compared the measurements and analysis of high-resolution 13C NMR spectra in B0 ≈ 16.5 T (NMR frequency of 175 MHz) with the results of SARA fractioning for four various heavy oil samples with viscosities ranging from 100 to 50,000 mPa·s. The presence of all major hydrocarbon components both in crude oil and in each of its fractions was established quantitatively using NMR spectroscopy. Contribution of SARA fractions in the aliphatic (10–60 ppm) and aromatic (110–160 ppm) areas of the 13C NMR spectra were identified. Quantitative fractions of aromatic molecules and oil functional groups were determined. Aromaticity factor and the mean length of the hydrocarbon chain were estimated. The obtained results show the feasibility of 13C NMR spectroscopy for the express analysis of oil from physical properties to the composition of functional groups to follow oil treatment processes.

scholarly journals 13C-nmr Spectroscopy to Monitor Sugars in Pitch of Internodes of a sh2 Corn at Developmental Stages

HortScience ◽  
1998 ◽  
Vol 33 (6) ◽  
pp. 980-983 ◽  
Author(s):  
V.M. Russo ◽  
J. Williamson ◽  
K. Roberts ◽  
J.R. Wright ◽  
N. Maness
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Nmr Spectra ◽  
Developmental Stages ◽  
Sweet Corn ◽  
Resonance Spectroscopy ◽  
C Nmr ◽  
Nuclear Magnetic

Sugars move through stalks to be deposited in kernels in sweet corn (Zea mays L.). Concentrations of sugars in stalks change as plants pass through developmental stages. To follow such changes, carbon-13 nuclear magnetic resonance spectroscopy (C-nmr), a technology that can measure concentrations of sugars in tissues, was compared with analysis by high-performance liquid chromatography (HPLC). A shrunken-2 hybrid (cv. Illini Gold), was monitored from mid-whorl to fresh-market maturity (R3). Internodes near the base of the stalk, just below the ear, and between an ear and the tassel were sampled at each developmental stage. Chemical shifts in C-nmr spectra were measured in parts per million hertz (ppm) down-field relative to tetramethyl silane. Through silk emergence (R1) C-nmr spectra were similar regardless of internode, having line positions between 60 and 105 ppm. Unique lines for glucose, fructose, and sucrose were at 96, 98, and 104 ppm, respectively, and mole fractions were similar to those determined by HPLC. The highest concentrations were recorded at R1 for sucrose (26.1 mg·mL-1), from tasseling (VT) through R3 for fructose (avg. 30.4 mg·mL-1), and from VT to R1 for glucose (avg. 32 mg·mL-1). Carbon-13 nuclear magnetic resonance spectroscopy can be used, with minimal sample handling, to monitor sugar concentrations in sweet corn.

The biosynthesis of caerulomycin A in Streptomycescaeruleus. Incorporation of 14C- and 13C-labeled precursors and analyses of labeling patterns by 13C nmr

1979 ◽  
Vol 57 (24) ◽  
pp. 3200-3204 ◽  
Author(s):  
A. Gavin McInnes ◽  
Donald G. Smith ◽  
John A. Walter ◽  
Leo C. Vining ◽  
Jeffrey L. C. Wright
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
13C Nmr ◽  
Diaminopimelic Acid ◽  
Resonance Spectroscopy ◽  
Nuclear Magnetic

Carbon-13 nuclear magnetic resonance spectroscopy of caerulomycin A (1) produced by cultures of Streptomycescaeruleus has shown that [1-13C]acetate labels C-2, C-4, and C-4′, whilst [1,2-13C]acetate enriches these carbons plus C-2′, C-3, C-3′, C-5′, and C-6′. The results establish that acetate is incorporated with little dilution at C-3 and C-4 in the substituted ring of 1, whereas C-2, and C-2′ to C-6′ of the unsubstituted ring, are assembled from lysine via the symmetrical intermediate 2S,6S-diaminopimelic acid. The methoxyl carbon incorporates label from DL-[3-13C]serine, but this precursor does not enrich C-5, C-6, or C-7 of the substituted ring, and the origins of these carbons remain undetermined.

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